There are two forms of sleep apnea known in the art. Central sleep apnea (CSA) is the loss of neurological drive to breathe. Obstructive sleep apnea (OSA) syndrome, the more common form of the two, is a physical obstruction of the oropharyngeal area of the upper airway. Due to morphology and neuromuscular tone, the tissue structures can close and remain closed for a prolonged period of time during sleep. These apneic episodes are followed by sudden attempts to breathe, which may cause partial arousal to a lighter state of sleep. The result is fragmented sleep, and, more importantly, cardiovascular disease and other diseases. Conventional therapy for OSA is delivery of continuous positive airway pressure (CPAP) from a pressure generator unit, delivered via a mask worn on the face, thereby, delivering positive pressure to the airway to keep the airway propped open.
OSA therapy is unique from all other forms of ventilation therapy in that the patient has to use the therapy only during sleep. Use during sleep requires that the therapy and devices be comfortable and un-obtrusive for a successful treatment. CPAP has significant unmet needs in that it is highly obtrusive and uncomfortable, because of which a majority of people with OSA remain untreated.
To address the limitations of CPAP, other therapies and interventions have been attempted. Less conventional therapies to treat OSA include tissue ablation, tissue resection, mandibular advancement appliances, implants, magnets and tissue suction devices. These approaches are all intended to prevent the obstruction of the oropharyngeal airway, however, each has disadvantages. Ablation and resection do not work because too much airway must be removed or reduced, thus affecting other airway functions, like swallowing and speech. Implants and magnets do not work because the procedures and devices either do not affect enough of the anatomy to prevent obstructions, or affect too much of the anatomy and adversely affect other airway functions. Suction devices and oral appliances do not work because of user unfriendliness.
Needs exist for approaches that prevent obstruction in a safe and effective manner, while at the same time preserving function of the oro-pharyngeal airway and avoiding any adverse side effects. Needs also exist for methods and apparatus that are less-obtrusive and more comfortable.
Other ventilation-based therapies using catheters or cannula have been described in the prior art. Jacobs (“Transtracheal Catheter Ventilation: Clinical Experience in 36 Patients”; Chest 1974; 65; 36-40) describes ventilating non-spontaneously breathing patients with a transtracheal catheter. McGinley (“A nasal cannula can be used to treat obstructive sleep apnea”; Am J Respir Crit Care Med. 2007 Jul. 15; 176(2):194-200) describes nocturnal treatment of OSA by nasal delivery of oxygen using modified oxygen therapy nasal prongs. Christopher (“Oxygen Therapy Using Pulse and Continuous Flow With a Transtracheal Catheter and a Nasal Cannula”; Chest 1994; 106:854-860) describes treating oxygen dependent patients using a transtracheal catheter for synchronizing the delivery of oxygen therapy to conserve oxygen. Breitenbücher (“Transtracheal oxygen therapy in obstructive sleep apnea syndrome”; Schweiz Med Wochenschr. 1989 Nov. 18; 119(46):1638-41) describes nocturnal treatment of OSA using a transtracheal cannula for continuous flow of gas. Christopher (U.S. Patent Publication No. 2005/0121038) describes a nasal catheter advanced toward the pharynx to directly ventilate the pharynx. Christopher (U.S. Pat. No. 5,954,050) describes a diagnostic transtracheal catheter equipped with respiration sensors used for diagnosing sleep apnea while providing continuous flow oxygen therapy.
While these catheter-based approaches have had some measure of clinical success, they are not effective enough to be embraced as mainstream therapies. The nasal cannula-based approaches tend to be effective with snoring or light OSA, but not moderate or severe OSA, because of the limited pressure it can create at the oropharynx. The transtracheal approaches tend not to have the fidelity and control system intelligence to make the therapies effective over a range of patient and clinical conditions, and, also, do not direct ventilation gas in the most optimal manner.
Needs exist for more effective ways to prevent or treat sleep apnea using catheter ventilation based systems and methods that address the aforementioned shortcomings.